Lift truck



July 8, 1947- J. R. HENDERSON LIFT TRUCK Filed Feb. 1, 1945 I 2Sheets-Sheet 1 BY M July 8, 1947. J, R. HENDERSON 2,423,703

' LIFT TRUCK Filed Feb. 1, 1945 I 2 Sheets-Sheet 2 q 51 W 47 30 I mfirm/Mira Patented July 8, 1947 UNITED STATE S PATENT OFFICE 11 Claims.

This invention relates to a relatively movable platform or likeincluding a portable truck, the platform portion being manually movableinto elevated and lowered position.

The chief object of this invention is to provide an auxiliary spring orsprings, normally directed to raise a certain portion of the grossweight of a load and elevating platform of a portable truck inassociation with means for positively raising and, if desired, loweringof the platform and load relative to the truck body. Usually this springforce is about half the total force required to elevate the maximumload. The result is that the amount of effort necessary to elevate aload is materially reduced and/or the time required therefor.

Herein the invention is disclosed as embodied in a truck wherein themeans for positively raising and lowering of the platform and load is ofthe fluid pressure operable type.

The chief feature of this invention resides in associating with alifting and lowering portion, such as a platform, of atruck of thecharacter described, a spring means arranged when released to assistother lifting means in load elevation.

In. lowering another means is effective to restore the spring means sosame can be held in the preloaded condition. y

Other objects and features of the invention will be set forth more fullyhereinafter.

The full nature of the invention will be understood from theaccompanying drawings and the following description and claims:

In the drawings.

Fig. 1 is a longitudinal sectional View through the elevating end of atruck, the hydraulic pump, reservoir, pump operating means, and truckguiding means being omitted, dotted lines indicating parts in anelevated position, the load in the loading and elevated positions alsobeing shown dotted and designated by letters A and B'respectively. V

Fig. 2 is a bottom plan view of those portions of the truck shown inFig; 1.

Fig. 3 is a view similarto Fig. 2 and of amultispring embodiment of theinvention.

Fig. 4 isa bottom plan view of a portion of a modified form of theinvention-,-with parts in section; this form being of the type whereinthe spring means is contained within .the hydraulic means.

Fig. 5 is a similar view of a'modified form. of the invention whereinthe spring means envelopes the hydraulic means.. I

Fig. 6 is a vertical seotic'inalxview of a'further 2 form of-theinvention and of the vertical" power type, and in the elevated position.

Fig. 7 is a diagrammatic view of' the hydraulic control system utilized.

In Figs. 1 and 2 of theinvention' Iii-indicates apair of frame membersof a portable truck provided with suitable wheel'm'eans foreand' aft,the latter only being illustrated herein and designatedb-y numeral 5 I.These wheels are supported on axle l2 suitably mounted in bearing meansl3 carried by the frame.

The platfomn herein includes base riser portion Hi. It is defined bydepending side flanges l6 and rear flange l'land may be mitred atthecorners as at !8 to facilitate platform entrance between runners C ofthe skid having platform D'suppor'ting load A, such as a pile of tinplate sheets. The clearance between the suppo-rti'ng'surface and underface ofthis slzid platform is such to permit truck platform positioningtherehetween and the runner spacing is sumci'ent to permit such platformpositioning; This is old in the art.

Pivoted at 26 in'fr'ame I0 upon member 2| is a rigid link member 22. Theplatform Mincludes bearings 23 for member 24 that pivotally connectsmember 22' to said platform.

Pivoted at 25in the frame Ill upon member 26 is a similar rigid link.member'- 21 that is'associated with member :28'carried' by bearingstructure ill-in turn carried by platform 14. Note that the link'members 22 and 21 are interchangeablean'd' constitute a parallel motiondevicel Herein frame H3 is braced by plates 30 provided" with alignedbearings 3i and member 32 therein between said plates pivotallysupports'the head 33 0f a power cylinder 34 having head 35 from whichprojects piston rod 36. Within this cylinder is a power piston. Fluidunder pressure is supplied to said cylinder by line 31 and at head 33.

Another cylin der38 includes head 39 connected to pressure supply lineAll and having pivot bearing ii carried by pivot 42 in turn carried bybearings 43 upon portion [3.

Similar bearings Git-support pivot dyin turn pivotally supporting cup 45seating one end of spring 45, the other end of which is seated in asimilar but oppositely directed cup 4'l.

Member '48 suitably secured to platform 14 provides aligned bearings 49that support member 50 which pivotally connects cup 41, rod 35 and rod5| to the platform. Rod 5l' mounts a piston (not shown) in cylinder 38.Rod 36 mounts a piston (not shown) in cylinder 34.

Operation is as follows: With pressure in piston 34, the spring 46, seeFig. 1, i .loaded for about half the total lifting force required forload and platform elevation to the dotted line position. When thepressure is released, the force of spring 46 is released for loadelevation.

Additional power then supplied by fluid pressure applied to cylinder 38elevates the load, etc., to the dotted line position. When the load iselevated, the truck is moved with the load to the new location. Then thepressure is released from cylinder 38 and the load and platform islowered by gravity, the spring 46 serving as a cushion or shockabsorber.

If the weight of the load is insufficient to over.- come the spring,fluid pressure is supplied to cylinder 34. In any event pressure must besupplied thereto to finally compress spring 45 and hold same compressedso that the truck platform under the skid base is free of the latter fortruck withdrawal. Pressure is retained in cylinder 34 to hold spring 48loaded-so that platform I4 can be positioned beneath another skidwhereupon the pressure in cylinder 34 is released and,

the cycle aforesaid is repeated.

As previously stated, the force of spring 46 is sufilcient to handleapproximately half the maximum load capacity of the truck. Whenever theload is less than that of the spring load, elevation is solely bypressure release in cylinder 34 and release of spring force. Platformlowering in this event, to effect load lowering, is effected by pressureapplication to cylinder 34, in addition to the Weight of the load,sufficient to overcome the spring force and return the spring to thefull line position, see Fig. 1, and hold same therein.

Reference will now be had to Fig. 3 wherein like parts have likedesignating numerals and similar parts are designated by numerals of theone hundred series similar to corresponding part designating numerals ofprimary series.

The only different parts herein are portion H3 with three pairs ofbearings, two designated by numerals I43 and the intermediate pair bynumerals I42 and portion I48 with spaced bearings I49, the outermostpair being positioned near the ends of member I 48 and the inner pairbeing somewhat elongated. Herein also rod I5I is bifurcated andstraddles rod 36.

Herein the power cylinder 38 is aligned with power cylinder 34 and twospring structures 45, etc., are provided one at each side of powercylinder 38. This is a better balanced arrangement and the two springs46 each may have half the force of the single spring 46 in Figs. 1 and2- with the resulting equal capacity structure, or each have thecapacity of spring 46 in said'Figs. 1 and 2 whereupon spring force willbe twice that of Figs. 1 and 2 structure.

In Fig. 4, a modified form of the invention is illustrated. In this formthe two cylinders again are aligned as in Fig. 3, but this form differsfrom those'illustrated in Figs. 1 to 3 in that the power springiscoaxial with the cylinder and not laterally offset therefrom a in theaforesaid forms.-

passes piston 260 provided with spaced ears 25I by which same is pivotedto the platform through member 250 in bearings 249 on plate 243.Operation of this embodiment is identical to that previously described.

In Fig. 5, the power cylinder head 338 includes spring seat extension338a. The piston rod 35I is shouldered at 35m and bearing thereagainstis cup 34! retaining the other end of spring 346, which herein envelopesthe power cylinder 33%. The piston rod 35I is bifurcated and retained bymember 350 in. bearings 34!) in plate 348 secured to the platform. Theoperation of this form is identical to that previously described.

Reference will now be had to Fig. 6 wherein a vertical embodiment isillustrated in the elevated position. Herein 6|!) indicates a portableframe,

' 6M a platform base, and 6I5 a riser rigid there- Herein the spring iscylinder enclosed. The form shown in Fig. 5 is similar, except thereinthe spring envelopes the cylinder. Numerals of the two hundred seriesand numerals of the three hundred'series in Figs. 4 and 5, respectively,designate parts similar or like those in Figs. 1 to 3.

InFig. 4 the cylinder 2 3 8 telecopes a bored piston 256] bored at 2M toseat spring 246. The free end of cylinder 238 is threaded at 238a andcap 262 threads thereon and retains packing 253 and with, the same beingconnected to the frame by links 622 and 621 at BZI and 626,respectively, and to the movable element as at 623-624 and 628629 asillustrated.

For purposes of illustration only, the form illustrated in Fig. 5 isembodied in Fig. 6, although it is to be understood that any of theother forms previously illustrated may be employed. Numerals ofthe 500series indicate parts like or corresponding to parts in Fig. 5designated by corresponding 30% series numerals. Operation of this formis identical to that previously described.

In Fig. '7 there is diagrammatically illustrated one form of hydrauliccontrol system, same being associated with pressure supply and releaselines 37 and 4t. Herein Qindicates a reservoir; 8 a pump included inline I with check valve la downstream of the pump. A return line 6 leadsto the reservoir from a valve unit.

This valve unit includes a valve 5 therein with arcuate passages 3 and 4therethrough and diametral passage 2 therebetween. Handle I is arrangedto shift the valve 5.. When the valve 5 is positioned as illustrated,pressure is supplied to cylinder 38 and pressure is released fromcylinder 34 to the reservoir to raise the platform and load. The degreeof port registration can control the force application.

When it is desired to forthwith release the load for gravity lowering,passage 2 is registered with lines 37 and 40 and fluid flows fromcylinder 38 to cylinder 34. When the platform and load are auxiliaryspring means supported, handle I is further turned to connect cylinder34 and line 31' to pressure line "I and cylinder 38 and line 40 toreturn line 5. Pressure from line I now actuates the piston in cylinder34 to load the auxiliary spring means as described.

When the load is to be elevated it can be released to the spring meansby registering passage 2 with lines 3'! and 40 and then by registeringlines I and 6 with cylinders 38 and 34,

respectively, ormoving immediately to the lat-.

connected together, the combinationof a pair,

of opposed fluid pressure operable means each having the remote endthereof connected to one means and the other end of said fluid pressureoperable means connected to the other of the said two first mentionedmeans and spring power means operatively interposed between the twofirst mentioned means and normally opposing one of the pressure operablemeans and assisting the other of said pressure operable means.

2. Structure as defined by claim 1. wherein the spring power means andone of the fluid pressure operable means are parallel to each other.

3. Structure as defined by claim 1 wherein the sprin power means is ofdual character.

4. Structure as defined by claim 1 wherein the spring power means is ofdual character and parallel to one of the fluid pressure operable means,the latter being therebetween.

5. Structure as defined by claim 1 wherein the spring power means is ofdual character and par allel to one of the fluid pressure operablemeans, the latter being therebetween and in longitudinal alignment withthe other fluid pressure operable means.

6. Structure as defined by claim 1 wherein the two fluid pressureoperable means are longitudinally aligned.

'7. Structure as defined by claim 1 wherein the spring power meansenvelopes one of the fluid pressure operable means.

8. Structure as defined by claim 1 wherein the spring power meansenvelopes one of the fluid pressure operable means and both pressureoperable means are longitudinally aligned.

9. Structure as defined by claim 1 wherein the spring power means isenclosed within one of the fluid pressure operable means.

10. Structure as defined by claim 1 wherein the spring power means isenclosed Within one of the fluid pressure operable means and bothpressure operable means are longitudinally aligned.

11. Structure as defined by claim 1 wherein the adjacent ends of thefluid pressure operable means have a common pivotal connection with thesaid other means.

JOHN R. HENDERSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,200,392 Goldberg May 14, 19401,074,753 Smouse Oct. 7, 1913

